I understood rule of thumb for selecting the ideal volume for a short board was to start at 1/2 your body weight.
Would give you maximum float then gauge down depending on ability, strength and amount of paddling you needed to do.
Width and rail shape will increase volume more than length.
Boards of the same volume will have different usable float when constructed with materials allowing the board to be lighter.
Volumes are sometimes quoted with board demensions and I generally can appreciate board sizing by volume.
But the equation seems can subjective???
Typical "White Bread" 6'1" x 191/2" x 21/2" generally ranges between 27 and 31 ltrs.
Looking at a slightly heavier version, rails are medium and told its 39.99Ltrs, questioned it but told volume is correct??
(Bene what d'ya think the new 6'1" drifter near 40ltrs).

Outline, rail shape, deck and bottom contours etc will change your volume...for example :

6'1" x 191/2" x 21/2 high performance shape with a domed deck and low knifey rails will have less volume than 6'1" x 191/2" x 21/2 with a flat deck boxy rails wide nose and fat tail...

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dowls said..
(Bene what d'ya think the new 6'1" drifter near 40ltrs).

40L per the BWS website 6'1" x 20' 3/8" x 2' 5/8". Heaps of width in the nose and the tail has a fair bit also.

The emergence of quoting volumes is due to machine/computer shaping - computer does the calcs. Too difficult to calculate volume for hand shaped boards, although if anyone has the equation please enlighten.

Diverse has some reading:
www.diversesurf.com.au/boards/boards/volume2.php

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dowls said..

I understood rule of thumb for selecting the ideal volume for a short board was to start at 1/2 your body weight.

Depends on ability. I aim for more like 1/3.

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bene313 said..

Too difficult to calculate volume for hand shaped boards, although if anyone has the equation please enlighten.

Put in bathtub. Measure water displaced.

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Legion said..

dowls said..

I understood rule of thumb for selecting the ideal volume for a short board was to start at 1/2 your body weight.

Depends on ability. I aim for more like 1/3.

I end up about same 30-40% (100kgs and 36-38L) and I'm not a good surfer so would have said the 50% would be on the high side, I'd say though that rocker definitely makes a big difference along with the vol.

Dowls - drifter 6'1" at 40l and given the shape I'm thinking you'll want be pretty big to kite it with it's full template, flat rocker as well as the volume.

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Legion said..

bene313 said..

Too difficult to calculate volume for hand shaped boards, although if anyone has the equation please enlighten.

Put in bathtub. Measure water displaced.

Yep, get your Archimedes on.

Half fill a bath, mark the water level. put your board in and submerge it fully, mark the new water level.

Pour in water 1L at a time to find the difference between line 1 and line 2. This is your boards volume.

Science is awesome.

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LateStarter said..

Science is awesome.

So is AKU Shaper and Shape 3DX

Have a play around on these dowels. You can download a free / light version of both - although AKUShaper will only last one month before they want some money. Take one of the basic templates / board outlines (that is similar to the one you are thinking about) that they have and put in the length, width and thickness of this board. There are a few video tutorials to watch to get you started but they are both pretty straight forward programs to use. AKU Shaper "up and comer" is probably the easiest of the two. But 3D gives you more scope. Then play around by adjusting the thickness by 1/4 to 1/2 an inch whilst keeping everything else the same, then play with widths. Finally play with the length. This will give you a really good idea of just what part of the board can give you a nice rise or drop in volume. Then as Tux talks about start to play around with the tail shapes and then the rails - boxy or knifey. You will see how quickly things change. Some things will surprise you I am sure but very quickly (after an hour of playing around) you will quickly develop a few little rules that you can use going forward. Rocker as some have mentioned here plays a massive part was well in the performance of the board for paddling but after playing around with these other 5 elements you will quickly develop a feel for the range of change in volume given a change in one or several of these characteristics. Then start playing around with your other boards to see how things would change if they were a touch wider, shorter or thicker - and you can then start to imagine how it would actually impact you when paddling. Like would a 10% drop in volume really impact me that much? What does a 10% drop in volume look like on my present quiver? Could I paddle my board if it had 10% less volume ? Would I really notice the difference if it was a 6'2" instead of a 6'4"? Or if it was 2 1/2 or 2 5/8 or 19.5 or 20? What would happen if my board had less boxy rails? Then play around with other board shapes e.g guns - which are longer and more slender and see if you get the same results. You might end up very surprised. If you get really excited then you can start playing around with concaves, vee etc but for now keep things simple as they can take a while to master with the software

Now be warned though. Playing with this software can be very very addictive and you may find yourself designing your own boards in no time. Then you can just get them cut out (you just email the file off to a place with a CNC machine) and hand finish them or get someone else to do it for you. Then you will want to learn to shape from scratch and this is where the real fun begins. Be warned And at worst you will develop a better understanding of how these elements combine to influence volume.

Thanks all.
Rule of thumb 1/3 man that's a low volume sadly my grommet days are over
Bene still think BWS are wrong drifter couldn't increase 10ltrs from each size.
Ted I'm on it AKU.
Shapers Australia at Currumbin support those doing their own boards.
Cheers

I doubt the drifter vol is wrong, it would have come from a program. They've stretched it 4" added almost 2" in width and 3/8" in thickness none of which is insignificant as I'd think with the thickness increase they 'd be carrying a bit of extra volume in the rails also

That volume sounds easily correct, its very wide & not much thinner than normal.

Also important to consider with volume. 2 boards of different dims but with the same volume, may not have the same float. A board with a larger lets say horizonal surface area will float more than a board with less. Like 4x1 will be floatier than 2x2 if that makes any sense. So although that boards slightly thinner, its width will give it plenty of float to make it easy to paddle into waves provided the rocker isn't pushing too much water.

bit of a moot point but what you are really talking about is density although the surfboard industry has (rightly or wrongly) adopted volume as the norm for hi-tech comparison a small block of concrete can have a volume of 30 litres but it sure as sh8t ain't going to ride like a 6'0 pyzel thruster or you can have a 5'4 fish with the same volume
on the plus side it can be handy when comparing very similar shaped boards with similar surface area ,bottom rocker plan shape and rail definition are the things that i look for in new board and you generally only get a bit of say in those if you have a local custom made board or shape one yourself . I had the benefit of sharing a house with a shaper for a number of years but before then i knew bugger all about the boards i was riding
having said that 40 L sounds like a big board compared to what some of the boards from JS and pyzel are offering
www.pyzelsurfboards.com/

FireWire have a volume calculator....but I reckon their figures are a bit on the high side. It says my range is 35 to 41 litres but 36 is more than enough....actually prefer 35.

I think you should read this.

www.seabreeze.com.au/forums/Surfing/Shortboards/starboard-day-Adelaide/

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Ctngoodvibes said..

FireWire have a volume calculator....but I reckon their figures are a bit on the high side. It says my range is 35 to 41 litres but 36 is more than enough....actually prefer 35.

I'm not convinced about their guide either,,, there are a few too many variables.
They put me in the 50-60ltrs range,. wt?
and I've just gone from 40 down to 35ltrs, and thinking its great . Could go lower.
I'm no whale at 80kgs. age and barely intermediate. Even if I was 10 years younger they're only going to drop it to 45ltrs.

^^
This is the lost version.

Takes a minute to get the hang of and you need to read the stuff around it

lostsurfboards.net/whats-your-guild-factor-surfboard-volumes-explained/

^^^
Thanks , that actually makes truckloads more sense.. puts me in the low to mid 30's ,
which I think is starting feel pretty comfortable.

Thanks SP had heard of Guild Factor but never understood the concept.
That's a great chart of Lost.

Cheers

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Ctngoodvibes said..

FireWire have a volume calculator....but I reckon their figures are a bit on the high side. It says my range is 35 to 41 litres but 36 is more than enough....actually prefer 35.

Its been about 18 months since I've played with the firewire one. It seems like its changed its calculation a bit. It used to say 26-31 for me, but its now saying 30-33 in good waves & they've included weak waves on there now. I'm the same as you, I like about 35.

The calculator SP posted would probably be fine if I were 1/2 my age.....& less lazy